Recently, mobile electronic devices equipped with electronic cameras using image sensors to electronically record subject images have been used widely. Some known electronic cameras provided in such mobile electronic devices have a face detection function. An example of such device is disclosed in JP-A-2006-227080.
The face detection function is a function to detect a subject face existing in a captured image as a face region to automatically focus on the subject face.
In an electronic camera, for reasons related to hardware configuration, there is an “unfocusable area” where a success rate of focusing on a subject is low that the area can be regarded as unfocusable (for example, areas of the upper and lower (left and right) several percentages of a captured image). When the face region of the subject is also detected in the whole image including the unfocusable area, the time of processing for detection may be elongated to spoil the usability. In addition, when a face region which is unfocusable though is displayed, a user may select the face region existing in the unfocusable area as a target of focusing.
The detected face region is displayed on a display of the mobile electronic device together with the captured image. When there are a plurality of subject faces in the captured image, a plurality of face regions are detected by the face detection function. Generally, the display of the mobile electronic device does not have a large display area. Therefore, the maximum displayable number of detected face regions is limited to keep the visibility of a captured image screen.
Here, the user is requested to perform operation to select one face region as a target of focusing from the detected face regions. For example, when the number of subjects is eight, the user has to perform an operation to select one region from detected face regions of the faces of the eight persons.
On this occasion, when the aforementioned maximum displayable number of face regions is set at a large number (for example, eight), all the eight persons who are the subjects will be displayed on the display. However, any other face region than the face region to focus on may be detected concurrently to increase the number of operations for selecting the desired face region.
On the other hand, when the maximum displayable number of face regions is set at a small number (for example, four), only face regions of four of the eight subjects will be displayed. As a result, a face region to focus on may be not displayed on the display. On this occasion, the user has to once put the subjects out of the frame and detect faces again. Thus, undesired rework may occur.
In this manner, when there are a plurality of faces in a captured image, the usability may be spoilt regardless of whether the displayable number of face regions is increased or decreased.